2-Amino-5-(substituted or unsubstituted phenylalkyl)1,3,4-thiadiazoles for treating anxiety

ABSTRACT

2-Amino-5-(substituted or unsubstituted phenylalkyl)-1,3,4thiadiazoles, e.g. 2-amino-5-(2-phenethyl)-1,3,4-thiadiazole, prepared, e.g. by ring closure, of corresponding 1-(substituted or unsubstituted phenylalkanoyl)-thiosemicarbazide in a strong acid medium. The compounds are useful as minor tranquilizers and sedative hypnotics.

United States Patent m1 Eberle et al.

[ NOV. 11, 1975 l l 2-AMINO-5-( SUBSTITUTED OR UNSUBSTITUTEI) PHENYLALKYL)1,3,4-THIADIAZOLES FOR TREATING ANXIETY [75] lnventorsi Marcel K. Eberle. Madison; Robert E. Manning, Mountain Lakes both of NJv [73] Assignce: Sandoz lnc., Ew Hanover NJ.

[22] Filed: July 23, I973 [2l] Appl. N0.: 381,895

Related U.S. Application Data [63] Continuation-in-purt of Scr Nu. 1l8.55l-' .lanv I7. 1972 abandoned. and a continuation-in-part of Serv N0. 218.559v Jan I7 1972 which is a continuation-impart of Ser No, 124.489, March 15. l97 l abandoned.

[52] U.S. Cl. 424/270 [51] Int. Cl. i. AGIK 31/425 [58] Field of Search 424/270 [56] References Cited OTHER PUBLICATIONS Chem Abst. 68 (1968) 6900lX. Chem Abst. 70 H973) 25366U,

Primary Em!r1iner-Stanley J. Friedman Armmvy Agent, or Fz'rmGerald D. Sharkin; Robert 5. Honor [57] ABSTRACT 9 Claims, N0 Drawings Z-AMINO-S-(SUBSTITUTED OR UNSUBSTITUTED PHENYLALKYL)1.3.4-THIADIAZOLES FOR TREATING ANXIETY This application is a continuation-impart of copending application Ser. No. 218.558. filed Jan. 17. 1972. now abandoned and copending application Ser. No. 218.559. filed Jan. 17. l972. the latter in turn being a continuation-in-part ofSer. No. 124.489. filed Mar. 15. 1971 now abandoned.

This invention relates to the use of certain 2.5-substituted thiadiazoles. More particularly. it relates to the use of certain 2-amino-5-( substituted or unsubstituted phenylalkyl)-l.3.4-thiadiazoles. as minor tranquilizer and sedative hypnotic agents.

The compounds with which this invention is concerned may be represented by the following structural formula:

N-H (I) R i where R,. R R R 4 and R are independently hydrogen. or lower alkyl having 1 to 4 carbon atoms. e.g. methyl. ethyl. propyl. isopropyl. butyl. or isobutyl. and

Z is (CH where n is l. or 2.

The compound of formula (I) where R,. R. R R

and R are hydrogen. and Z is -(CH where n is l. is known and may be prepared according to the methods disclosed in the literature from known starting materials.

All the compounds of formula (I) may be prepared by the following reaction scheme A:

2 v R3 R1 a i /I 2 R z n \g/ 1-- N 1. L mx wherein R R R R R and Z have the above stated significance. The compounds of formula (I) may be prepared by ring closure of a compound of formula (ll) in a strong Lewis acid medium such as phosphoric acid. hydrochloric acid. sulfuric acid. and the like. or a halogenated phosphoric acid. such as phosphorous tribromide. at a temperature of from 40 to l00C.. preferably to C. for about 0.5 to 20 hours. preferably 2 to 6 hours. Though a solvent is not necessary. inert aromatic solvents such as benzene. toluene. xylene. chlorobenzene and the like may be used. Neither the temperatures nor the times used are critical.

The compounds of formula (I) may also be prepared by the following reaction scheme 8:

8 NH -NH-C-HH Rh ZC-X (III) .L i R l s r:s,

wherein R R R R R and Z have the above stated signifi canoe. and

X is halo having an atomic weight of 35 to 80.

The compounds of formula (I) may be prepared by treating a substituted or unsubstituted phenylalkanoylhalide. e.g. 3-phenylpropionyl chloride. with thiosemicarbazide in a strong Lewis acid medium such as described respecting scheme A. at a temperature of from 40 to C preferably 50 to 60C. for about 0.5 to 20 hours. preferably about 2 to 6 hours. Though a solvent is not necessary. inert solvents such as described respecting scheme A may be used if desired. Neither the temperatures nor the times used are critical.

The compounds of formula (ll) may be prepared by the following reaction scheme C:

f; rrri -m-1-c-Na R (z)-c-x R Z N/ r/ where R R R R.. R Z and X have the above stated significance.

The compounds of formula (ll) may be prepared by treating a compound of formula (lll) with thiosemicarbazide in an inert solvent such as dialkyltormamide. e.g. dimethylformamide. at a temperature of from to 80C.. preferably to 50C.. for about 1 to 24 hours. preferably 2 to 6 hours. Neither the solvents nor the temperature or time used are critical.

The compounds of formulas (l) and (ll) may be recovered by conventional recover techniques such as crystallization.

Certain of the compounds of formula III) are known and may he prepared by methods disclosed in the literaturev Those compounds of formula (111) not specifically disclosed may be prepared according to analogous methods from known materials.

The compounds of formula (I) are useful because they possess pharmacological activity in animals. ln particular. the compounds are useful as tranquilizers and sedative hypnotics. as indicated in the mouse given typically 24-200 mg/kg of body weight of the active compound and tested using the 30-word adjective test basically as described by Irwin. S. (Gordon Research Conference. Medicinal Chemistry. 1959) and Chen (Symposium on Sedative and Hypnotic Drugs. William and Wilkins. 1954). the chemically induced seizures test basically as described by Orloff. et al.. (Proc. Soc. Exp. Biol.. 70 354. 1949). and the hexobarbital reinduction test. wherein immediately after the animals recover their righting reflex which was lost upon the administration of hexabarbital. reinduction is stated to occur if the animals once again lose their righting reflex.

For such usage, the compounds may be administered orally or parenterally as such or admixed with conventional pharmaceutical carriers. They may be administered orally in such forms as tablets. dispersible pow ders. granules. capsules. syrups and elixirs, and parenterally as solutions. suspensions. dispersions, emulsions. and the like. c.g. a sterile injectable aqueous suspension. The compositions for oral use may contain one or more conventional adjuvants. such as sweetening agents. flavoring agents. coloring agents and preserving agents. in order to provide an elegant and palatable preparation. Tablets may contain the active ingredient in admixture with conventional pharmaceutically acceptable excipients, e.g. inert diluents. such as cal cium carbonate. sodium carbonate. lactose and talc. granulating and disintegrating agents. e.g. starch and alginic acid. binding agents. cg. starch, gelatin and acacia. and lubricating agents. e.g. magnesium stearate, stearic acid and talc. The tablets may be uncoated or coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period. Similarly. suspensions, syrups and elixirs may contain the active ingredient in admixture with any of the conventional excipients utilized for the preparation of such compositions. e.g. suspending agents (methylcellulose. tragacanth and sodium alginate). wetting agents (lecithin. polyoxyethylene stearate and polyoxyethylene sorbitan mono-oleate) and preservatives (ethyl-p hydroxybenzoate). Capsules may contain the active ingredient alone or admixed with an inert solid diluent.

e.g. calcium carbonate. calcium phosphate and kaolin.

The dosage of active ingredient employed for the tranquilizer and sedative hypnotic use may vary depending on the severity of the condition being treated. However. in general. satisfactory results are obtained when a compound of formula (I) is administered at a daily dosage of from about 2 milligrams to about 200 milligrams per kilogram of animal body weight. preferably given in divided doses 2 to 4 times a day. or in sustained release form. For most larger mammals. (e.g. primates) the total daily dosage is from about 150 to about 2.000 milligrams. Dosage forms suitable for internal use comprise from about 37.5 to about 1.000 milligrams of the active compound. in intimate admixture with a solid or liquid pharmaceutically acceptable carrier or diluent.

EXAMPLE 1 2H 2-amino-S-( Z-phe nethyl l .3.4-thiadiazole.

Step A. l-( 3-phenylpropionyl )-3-thiosemicarbazide.

A mixture of 9.9 g. of 3-phenylpropionylchloride and 4.6 g. of thiosemicarbazide was stirred in ml. of dimethylformamide for 6 hours. at 22C The solvent was evaporated and 10 ml. of water and 10 ml. of ether were added to the residue. The precipitate was filtered off to give the intermediate 1-(3-phenylpropionyl)-3- thiosemicarbazide. m.p. 140l4 1C.

Step B. 2-amino-5-( Z-phenethyl l ,3 .4-thiadiazole.

A mixture of 5.0 g. of l-(3-phenylpropionyl)-3-thiosemicarbazide (from Step A) and 5.4 g. of phosphorous tribromide was heated to 6065C. for 2 hours. After cooling. 50 cc. of cold water and then 3 cc. of a 50% sodium hydroxide solution were added. The product. 2ami1io-5-(2-phenethyl)-l .3.4-thiadiazole. m.p. 184-l 86C. was precipitated.

EXAMPLE 2 Step A Following the procedure of Example 1. Step A). and in place of 3-phenyl-propionylchloride and starting with a 2-( o-methylphenyl )acetylchloride.

M b. 2-(pmethylphenyl)acetylchloride.

i c. Z-(S-methylphenyl)acetylchloride. or d. 2-( 2 .-dimethylphenyl )acetylchloride Step B Following the procedure of Example 1. Step (B). and starting with the appropriate intermediate of Step (A) of this Example. the following products are obtained a. 2-amino-5-( Z-methylbenzyl l .3.4-thiadiazole.

b. Z-amino-S-(p-methylben2yl)-1.3.5-thiadiazole.

c. 2-amino-S-( 3-meth ylbenzyl l .3.4-thiadiazole. or

d. 2-amino-5-(1.6-dimethylbenzyl)- l .3.4-thiadiazole.

respectively.

EXAMPLE 3 Z-amino-5-( 'l-phenethyl l-l .3.4-thiadiazole.

A mixture of l7.7 g. of 3-phenylpropionylchloridev 8.2 g. of thiosemicarbazicle and 8.1 g. of phosphorous tribromide was heated to 60C.. when an c\othermic reaction occurred raising the temperature to ll)UC. The reaction mixture was cooled to 50 to 60C. for hours (when the evolution of hydrogen bromide ceased]. and llll) cc. of ice water added. The mixture was then treated with ll] cc. of 5092 sodium hydroxide solution. the resulting solid was washed with ZN sodium hydroxide solution and water. and the product crystallized from dimethylforamide and water. 2t1mino 5-( Z- EXAMPLES 7 and 8 Sterile Suspension for Injection and Oral Liquid Suspension.

The following pharmaceutical compositions are formulated with the indicated amount of active agent using conventional techniques. The injectable suspen sion and the oral liquid suspension represent formulations useful as unit doses and may be administered as minor tranquilizers and sedative hy pnotics. The injec- ])l'tCllt?Ih \lhljsl-IllltltllttZOlE. mp l84l86C. 1 table suspension is suitable for administration once a HXAMPL E 4 day whereas the oral liquid suspension is suitably administered I to 4 times per day for this purpose.

Weight 1mg) Sterile Oral Ingredients lnjectablc Suspension Liquid Suspension 2 amino-54 Z-phenethyl Jl .3.-Lthiadia1.ole I 5 sodium carbo\ methyl cellulose LISP L15 ll. methyl cellulose (t-l poly in; lp rrolidone 5 f lecithin 3 bemyl alcohol (Mil magnesium aluminum silicate 47 S fla\ or qs color as methyl purahen. L.S.P. 4.5 propyl paraben. L SP. l.ll polysorbate 8U leg. Tween SUI. L SP. 5 sorbitol solution Ttl'r. L.S.P. 15W) buffer agent to adjust pH for desired q.s. q.s.

stability .iler

for injection qr to l ml. q s. to 5 ml.

Following the procedure of Example 3. and in place of 3-phenylpropionylchloride and starting with a. 2-( o-methylphenyl)acetylchloride.

b. 2-(p-methylphenyl)acetylchloride,

e. 2-( S-methylphenyl )acety'lchloride or d. 2-( lo-dimethylphenyl )acety'lchloride,

following products are obtained 2-amino-5-( Q-methylbenzyl l ,3.4-thiadiazole, 2-amino-5-( p-methylbenzyl l .3,4-thiadiazole 2-amino-5 (3-methylbenzyl)-1,3,4-thiadiazole, or 2-amino-5-( lo-dimethylbenzyl l ,3,4-thiadiazole,

respectively.

EXAMPLES 5 and 6 Tablets and Capsules Suitable for Oral Administration.

Tablets and capsules containing the ingredients indicated below may be prepared by conventional techniques and are useful as minor tranquilizers and sedative hypnotics at a dose of one tablet or capsule 2 to 4 times a day.

Ingredients Weight (mg) tablet capsule 2-amino5-l l-phenethy l l .3.-l- 15 I5 thiadiazole trttgacanth lU lactose 122.5 175 corn starch 25 talcum l5 magnesium stearate Sterile injectable suspensions and oral liquid suspensions may be prepared in a similar manner as above cmploy'ing each of the final products of Example 4. namely (a), (b). (c) or (d) as the active ingredient.

What is claimed is;

l. A method for treating anxiety which comprises administering to a mammal in need of said treatment a tranquilizing effective amount of a compound of the formula 5. A method according to claim 1 in which the compound is Z-amino-5-( p-methylbenzyl )-l 3.4- thiadiazole.

6. A method according to claim 1 in which the compound is 2-amino-5-( 3-methylbenzyl l 3.4- thiadiazole.

7. A method according to claim I wherein the compound is administered orally at a daily dosage of from about 150 milligrams to about 2000 milligrams.

8. A method according to claim I wherein the compound is administered in a unit dosage form comprising said compound to the extent of from about 37.5 milligrams to about lOUU milligrams per unit dosage.

9. A pharmaceutical composition useful as a tranquilizing agent comprising as an active ingredient thereof a compound of the formula m where 

1. A METHOD FOR TREATING ANXIETY WHICH COMPRISES ADMINISTERING TO MAMMAL IN NEED OF SAID TREATMENT A TRANQUILIZING EFFECTIVE AMOUNT OF A COMPOUND OF THE FORMULA
 2. A method according to claim 1 in which the compound is 2-amino-5-(benzyl)-1,3,4-thiadiazole.
 3. A method according to claim 1 in which the compound is 2-amino-5-(2-phenethyl)-1,3,4-thiadiazole.
 4. A method according to claim 1 in which the compound is 2-amino-5-(2-methylbenzyl)-1,3,4-thiadiazole.
 5. A method according to claim 1 in which the compound is 2-amino-5-(p-methylbenzyl)-1,3,4-thiadiazole.
 6. A method accordiNg to claim 1 in which the compound is 2-amino-5-(3-methylbenzyl)-1,3,4-thiadiazole.
 7. A method according to claim 1 wherein the compound is administered orally at a daily dosage of from about 150 milligrams to about 2000 milligrams.
 8. A method according to claim 1 wherein the compound is administered in a unit dosage form comprising said compound to the extent of from about 37.5 milligrams to about 1000 milligrams per unit dosage.
 9. A pharmaceutical composition useful as a tranquilizing agent comprising as an active ingredient thereof a compound of the formula 